The Isolation Manifold, lessons not learned and a small defence of the IUCRR

[Alaskan Scuba Dude]

I don't know anyone, who had his manifold closed by accident and if that happens i would be very cautious to dive with this diver, because there might be more fundamentals missing.

There will always be a weak link in the team chain and that is why the best technical divers call out and verify every piece of essential equipment just before hitting the water. Should a less experienced technical diver continually place the team in jeopardy, then that diver would be expelled from the team. We neither leave fallen divers behind nor do we castigate them when they are gaining that experience. I’m unaware if this is a G.U.E policy.

 

[Kay Dee]

There's nothing wrong with manifolds there needed with multiple tanks, the isolator is useless and creates problems. It introduces more potential leaks and in the time it takes to close the isolator the valve could be closed. I've never used an isolator the minute I saw one I thought why would I add that to my tanks, what will it do for me?

If you had one and had learnt how to set it and then close it properly whilst u/w it just might save you're arse. I have seen more people 'saved' by an isolator manifold (shutdown when in extremis) than I have seen killed by one.

 

[Vicko]

If you had one and had learnt how to set it and then close it properly whilst u/w it just might save you're arse. I have seen more people 'saved' by an isolator manifold (shutdown when in extremis) than I have seen killed by one.

Can you explain how the isolator helped and a manifold without one would not?

 

[Raphus]

There's nothing wrong with manifolds there needed with multiple tanks, the isolator is useless and creates problems. It introduces more potential leaks and in the time it takes to close the isolator the valve could be closed. I've never used an isolator the minute I saw one I thought why would I add that to my tanks, what will it do for me?

Sorry, this is cause by my bad english.
I was talking about a isolated manifold.

It can safe you life, if a leak happens, that is not solved by closing the tank valve. Eg. The valve itself or the oring between tank and salve.
I know someone who had this on a tech dive and it safed his life.

 

[Celt]

If you had one and had learnt how to set it and then close it properly whilst u/w it just might save you're arse. I have seen more people 'saved' by an isolator manifold (shutdown when in extremis) than I have seen killed by one.

I learnt to shut the offending valve, why would I waste time shutting an isolator. A problem with a second stage is obvious and simply shut the appropriate valve. I check my valves in the water before putting my tanks on for leaks at the first stages, if I had a catastrophic leak at a first stage in the water ( which I've never had) I'd pull the tank over my head and shut the proper valve immediately not play around with an isolator.

 

[Alaskan Scuba Dude]

Can you explain how the isolator helped and a manifold without one would not?

He would be referring to shutting down an isolation valve on the manifold fitted with burst disks on the tank valve.

 

[Celt]

Sorry, this is cause by my bad english.
I was talking about a isolated manifold.

It can safe you life, if a leak happens, that isn't not solved by closing the tank valve. Eg. The valve itself or the oring between tank and salve.
I know someone who had this on a tech dive and it safed his life.

It could just as easy be the isolator thats leaking. If there's a problem with a neck oring it will show on the surface when the tank is under the greatest pressure. A tank valve should be metat to metal and when you see an extruded oring it's more than likely the wrong oring

 

[Julius SCHMIDT]

Many of us are critical of the lack of accident analysis that comes out of the IUCRR. I feel we need accident analysis to spot patterns systemically so that as a community and industry we can learn, mitigate and make it safer.
BUT... let's talk about something, that in my almost 3 decades teaching technical diving I have observed as well, the dual isolation manifold. It IMHO has killed and hurt more people than it has saved. It sounds logical, so much so that virtually every agency requires the use of them in standards when teaching in doubles. However, what it solves is exceptionally rare, while people diving with it shut and thinking they ran out of air and doing rocket assents, drownings etc. and also filling mistakes that has also killed and hurt people is not unheard of at all (I have witnessed a couple) and dives where the diver ran out of gas yet recognized the problem and did the isolator open and "squeal of shame" is not uncommon.

So, what does this have to do with the IUCRR?

Ok, we want accident reports for safety, they have moved away from for worry over lawsuits and also a oft cited philosophy that the rules of cave diving are known, people die when they break the rules so nothing is to be learned anyhow (strongly disagree).

So, let's connect the IUCRR and manifolds, they posted this back in 2005 manifolds article 1, and manifold article 2 , they are correct.
In the passing 17 years, no agency had a serious look at it that I am aware (and heck, I tried at one when on BOD), they remain a required standard, they are still so much accepted that you virtually never see a non isolating crossover and accidents continue to happen.

Given that, why would the IUCRR believe that accident analysis will change anything?
This is one of those situations where even if you show the data, even if you convince folks (agencies/instructors/manufs) that they are not safer, there will be an unwillingness to advocate a change because it means they were "wrong" and have to admit it, plus fight an uphill battle over with industry stakeholders and instructors/divers that having been taught are safer, will resist a change or re-thinking of the issue.


Just some food for thought

And now let us start again!

 

[Celt]

And now let us start again!

Sorry about that, the problem with accident reporting is people get defensive when an accident happens

 

[Vicko]

He would be referring to shutting down an isolation valve on the manifold fitted with burst disks on the tank valve.

That's what's the hang up in this discusion. The only problems that isolator fixes are the ones that happen during filling the tank or increasing the pressure due to heat, they are extremely rare and require severe neglect of the equipment to happen underwater. On the other hand there is a huge amount of people who get their day ruined because someone accidently closed the isolator before filling the tank.